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Research Article |
1 HM Research Associates, 2 Clive Road, Balsall Common CV7 7DW, UK
2 CASP, Department of Earth Sciences, University of Cambridge, 181a Huntingdon Road, Cambridge CB3 0DH, UK
3 British Geological Survey, Murchison House, West Mains Road, Edinburgh EH9 3LA, UK
4 Research School of Earth Sciences, The Australian National University, Canberra, ACT 0200, Australia
*Corresponding author (e-mail: a.c.morton{at}heavyminerals.fsnet.co.uk)
U–Pb dating of detrital zircons shows that the provenance of Cretaceous–Palaeogene sandstones on Hatton and Edoras banks (SW Rockall Plateau) comprises magmatic rocks dated at c. 1800 Ma and c. 1750 Ma, respectively. Their depositional setting, first-cycle mineralogy and unimodal detrital zircon populations suggest that these sandstones are of local origin. The zircon age data are therefore considered to provide constraints on these poorly understood areas of the Rockall Plateau. The U–Pb dates are directly comparable with U–Pb zircon crystallization ages from granitoid rocks reported from the Ketilidian Belt of southern Greenland and from the Rhinns Complex of western Britain. Hf isotopic data from the Edoras Bank sample are consistent with derivation from a juvenile Palaeoproterozoic block. In conjunction with previously reported Sm–Nd Tdm model ages from the Ketilidian Belt, Rockall Bank and the Rhinns Complex, these data extend the known distribution of a large juvenile Palaeoproterozoic terrane spanning the southern NE Atlantic. In contrast, Hf isotopic data from the Hatton Bank sample imply a large contribution from Archaean crust. The zircon population from Edoras Bank also contains sparse Mesoproterozoic grains, providing evidence for the presence of volumetrically minor Grenville-age intrusions in the southern part of the Rockall Plateau.
